Abstract Profilin(PRF) is a low molecular weight actin binding protein which is linked to the signal transduction cascade via the phosphoinositide pathways in eukaryotes, regulating both actin polymerization and depolymerization. To date, PRF has been identified in many higher plants, such as Arabidopsis thaliana, Zea mays, Akebia trifoliata, Brassica campestris. In this study, a cDNA clone(designated TaPRF7 (GenBank No. KY940299) in accordance with the accession sequence of wheat (Triticum aestivum) PRF in GenBank) encoding PRF gene was isolated from stamen of wheat photoperiod-thermo sensitive genic male sterile(PTGMS) line BS366 using RT-PCR technique. The cDNA sequence contains a 396 bp ORF, coding for 131 amino acids, with an estimated molecular mass of 14.2 kD and a pI of 4.81. Homology comparison revealed that the protein contains conservative PROF domain and actin, PIP2 and poly-L-proline (PLP) binding sites. The amino acid sequence among TaPRF7 and other different species (T. aestivum, Z. mays, Oryza sativa, Glycine max, Hordeum vulgare, Sorghum bicolor, A. thaliana, Nicotiana tabacum, Solarmum tuberosum) compared by Blast, revealing that there was high homology (70%~97%) with profiling protein of other plants and the similarity to TaPRF1(ACE82291.1) protein was the highest with 97%. Phylogenetic analysis showed that TaPRF7 has close relationship with ZmPRF2, ZmPRF4, ZmPRF5, HvPRF1, SbPRF and OsPRF. Subcellular localization analysis indicated that TaPRF7 was targeted to the nucleus and cytoplasm by detecting the fluorescent signals of eukaryotic expression vector in Arabidopsis protoplasts. Expressions of TaPRF7 had been observed in various tissues (root, stem, leaf, stamen, pistal and glume) of wheat, but was highest in stamen, followed by root, suggesting that TaPRF7 was reproductive expression and mainly expressed in reproductive organs. To investigate the involvement of TaPRF7 in signal transduction, TaPRF7 gene expression of wheat seedling in the abiotic stresses was studied. The results showed that expression of TaPRF7 was inhibited significantly by exogenous methyl jasmonate (MeJA) and salicylic acid (SA) treatments, while up-regulated under cold (10 ℃), abscisic acid (ABA), drought (PEG 6 000), gibberellin (GA), NaCl, indoleaceticacid (IAA) treatments. TaPRF7 expression speaked at different time in different abiotic treatments. The results showed that peaks appeared about 8 h after cold and NaCl treatments, 4 h after PEG and GA treatments and 2 h after IAA and ABA treatments, respectively, suggesting that TaPRF7 responses to many abiotic stresses. Further, the TaPRF7 expressions were decreased after they peaked. It was likely to be due to negative regulation which caused by accumulation of the gene. Microfilament is one component of cytoskeleton, and it is mainly composed of actin. Recent studies showed that movement of microfilament was involved in plant fertility. PRF as a microfilament-associated protein, maybe play important roles in fertility regulation. To investigate the role of TaPRF7 in fertility regulation, analysis of TaPRF7 expression profile between PTGMS line BS366 and coventional wheat line Jing411 during fertility transition was performed. It was found that TaPRF7 showed low expression and no significant change during fertility transitionin Jing411. However, the expression of TaPRF7 increased with the anther development in both sterile environment and fertile environment with the development of anther. Besides, the expressions of TaPRF7 were higher during fertility transition in sterile environment comparing with expression infertile environment. In summary, it was speculated that TaPRF7 may be involved in the signaling transduction for anther dehiscence and cold-induced male sterility associated with wheat male sterility. This study laid a basis for investigation of TaPRF7 in molecular mechanisms of wheat PTGMS line.
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